1. Field of the Invention
The present invention relates to the fields of organic chemistry and material sciences.
2. Brief Description of Related Technology
The state of the art recognises numerous methods for the functionalisation of surfaces. Such functionalisations are used in order to modify the material properties of the surfaces in a targeted manner. Such functionalisations should be as durable as possible and allow for a highly defined loading of the surface.
In the field of medical technology, special importance is place on functionalised surfaces. Implants should—by way of example in the dental industry and orthopedics (joint replacement)—be as biocompatible as possible, i.e. by not have, inter alia, having a tendency towards biofouling, not causing any inflammatory reactions and not being seeded with pathogenic microorganisms. Furthermore, they must permanently resist to heavy mechanical strain.
Medical implants frequently comprise frequently the metals iron and/or titanium, while dental implants also contain apatite. Until now, monomeric derivatives of the catecholamine have been used as a surface binder to which different functional molecules such as antibiotics or PEG were subsequently bonded. With such conjugates, it was possible to detect an increased resistance of the surfaces against biofouling. Polymer structures which imitate mussel adhesion proteins are an alternative to monomeric catechol derivatives. These are used as a biomimetic adhesive.
With the help of monomeric catechol derivatives, metal surfaces are suitable to be easily functionalised; however this functionalisation unfortunately comes with low durability. This is particularly disadvantageous in the case of heavy material stress such as applications in the dental industry. Although polymer structures allow for an extremely strong connection, they do not allow for a targeted or defined functionalisation of the surface as is desired, by way of example, for implants.
Methods suitable to coat antimicrobially surfaces with natural product hybrids are described in J-Y Wach, S Bonazzi, K Gademann: “Antimikrobielle Oberflächen durch Naturstoffhybride” (Antimicrobial surfaces by means of natural product hybrids), 120, 7232-7235. The natural product hybrids only comprise monomeric catecholamines.
Examinations with regard to structure-activity relationships of methylated or hydroxyterminated polyglycerol structures, which were deposited as SAMs on surfaces of gold, are described in M Wyszogrodzka, R Haag: “Study of Single Protein Adsorption onto Monoamino Oligoglycerol Derivatives: A Structure-Activity Relationship”, Langmuir 2009, 25, 5703-5712. The shown dendritic polyglycerol structures do not comprise any aromatic functional groups.
In J K Young, G R Baker, G R Newkome: “Smart Cascade Polymers. Modular Syntheses of Four-Directional Dendritic Macromolecules with Acidic, Neutral, or Basic Terminal Groups and the Effect of ph Changeson their Hydrodynamic Radii”, Macromolecules 1994, 27, 3464-3471 examples for the synthesis of fourdirectional, flexible and dendritic cascade polymers are described. The disclosed dendritic molecules, however, do not comprise any catecholamine groups, in a manner characteristic of mussel adhesion proteins.
In K Yoon, P Goyal, M Weck: “Monofunctionalization of Dendrimers with Use of Microwave-Assisted 1,3-Dipolar Cycloadditions”, Org Lett 2007, 9, 2051-2054, are also described methods for the production of flexible dendritic compounds. The work discloses, inter alia, the introduction of cyclic functional groups via 1,3-dipolar cycloadditions. M Kleinert, T Winkler, A Terfort and T B Lindhorst describe in “A modular approach for the construction and modification of glyco-SAMs utilizing 1,3-dipolar cycloaddition”, Org Biomol Chem 2008, 6, 2118-2132 also methods for the modular synthesis of flexible dendritic compounds. In addition to 1,3 dipolar cycloadditions are also described click reactions on SAMs.
In S K Sahoo, B K Kanungo, M Baral:, Complexation of a tripodal amine-catechol ligand tris(2,3-dihydroxybenzylamino)ethyl)amine towards Al(III), Ga(III), and In(III), Monatsh Chem 2009, 140, 139-145 trivalent flexible frameworks with catecholamine ligands are described. The trivalent flexible frameworks are tertiary aliphatic amines, and the catecholamines have a 2,3 dihydroxy substitution pattern. The disclosed compounds do not allow for a functionalisation with effectors, and are therefore only in a limited way usable for the functionalisation of surfaces. When the compounds are used as metal chelators no additional functionality, for instance for the cell or pathogenic recognition, is suitable to be introduced.